Photoreversible Supramolecular Polymerisation and Hierarchical Organization of Hydrogen‐Bonded Supramolecular Co‐polymers Composed of Diarylethenes and Oligothiophenes |
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| Authors: | Prof?Dr Shiki Yagai Keisuke Ohta Marina Gushiken Kazunori Iwai Atsushi Asano Prof?Dr Shu Seki Dr Yoshihiro Kikkawa Prof?Dr Masakazu Morimoto Prof?Dr Akihide Kitamura Prof?Dr Takashi Karatsu |
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| Institution: | 1. Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1‐33 Yayoi‐cho, Inage‐ku, Chiba 263‐8522 (Japan), Fax: (+81)?43‐290‐3039;2. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2‐1, Yamadaoka, Suita, Osaka 565‐0871 (Japan);3. Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1‐1‐1 Higashi, Tsukuba, Ibaraki 305‐8562 (Japan);4. Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, Nishi‐Ikebukuro 3‐34‐1, Toshima‐ku, Tokyo 171‐8501 (Japan) |
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| Abstract: | Diarylethene 1 equipped with two monotopic melamine hydrogen‐bonding sites and oligothiophene‐functionalized ditopic cyanurate (OTCA) were mixed in a nonpolar solvent to form AA‐BB‐type supramolecular co‐polymers (SCPs) bearing photoswitchable moieties in their main chains and extended π systems as side chains. UV/Vis, fluorescence, dynamic light scattering (DLS), TEM, and AFM studies revealed that the two functional co‐monomers formed flexible quasi‐one‐dimensional SCPs in solution that hierarchically self‐organized into helical nanofibers through H‐aggregation of the oligothiophene side chains. Upon irradiating the SCPs with UV light, a transition occurred from the H‐aggregated state to non‐aggregated monomeric oligothiophene side chains, as shown by spectroscopic studies, which indicates the formation of small oligomeric species held together only by hydrogen‐bonding interactions. TEM and AFM visualized unfolded fibrils corresponding to elongated single SCP chains formed upon removal of solvent. The helical nanofibers were regenerated upon irradiating the UVirradiated solution with visible light. These results demonstrated that the supramolecular polymerisation followed by hierarchical organization can be effectively controlled by proper supramolecular designs using diarylethenes and π‐conjugated oligomers. |
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| Keywords: | diarylethenes oligothiophenes photoresponsive assemblies self‐assembly supramolecular polymers |
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